Hi

Please watch this video and tell if this really can be true?, to know if the component fake or original?

 

Chip size is only one of several things that you could examine to determine whether the device is fake or not. It would tell you, in an indirect way, whether the device may be able to carry the rated current.

Unfortunately, there are other parameters, like maximum Vceo or Vdss, or hfe, or Vgs(th) that would require a curve tracer to determine.

 

Some simple test schemes involve an oscillator that delivers a bit of power. A mosfet with inadequate gain will not deliver the expected output. a worse device will fail more completely. Not a complete test, but often enough to separate the sheep from the goats. and from the pigs.